1. Field of the Invention
The present invention generally relates to a steering assist system and, more particularly, to a method for assisting the steering of a marine vessel which has two or more marine propulsion devices.
2. Description of the Related Art
Various techniques have been used in the past to assist the steering of a marine vessel or watercraft through the control of the thrust generated by a marine propulsion device associated with the marine vessel or watercraft. In addition, it is generally known that the manipulation of the trim tabs of a marine vessel can assist is in vessel control and, in certain applications, in the steering system of a marine vessel or watercraft.
U.S. Pat. No. 6,174,210, which issued to Spade et al. on Jan. 16, 2001, describes a watercraft control mechanism comprising a steerable propulsion source, a steering controller for controlling the steerable propulsion source, a linking member connected to the steerable propulsion source, and at least one tab connected to the linking member. The tab is movable between an inoperative position and an operative position whereby the tab can be angled such that, in the operative position and when the watercraft is traveling upright in water in a substantially forward direction, a volume of water impinges on a top surface of the tab, thereby creating a downward and rearward force on the watercraft.
U.S. Pat. No. 6,405,669, which issued to Rheault et al. on Jun. 18, 2002, describes a watercraft with steer response engine speed controller. The control system provides thrust for steering control in a watercraft that is powered by a propulsion unit. The steering control system is applicable to various types of watercraft, including boats and personal watercraft, that are powered by inboard jet propulsion systems or outboard engines. The system is activated by the steering helm assembly and/or an electronic control mechanism.
U.S. Pat. No. 6,428,371, which issued to Michel et al. on Aug. 6, 2002, describes a watercraft with steer responsive engine speed controller. The controller generates thrust when the steerable propulsion unit is turned beyond a predetermined angular threshold. Turning the steering wheel beyond the threshold causes the speed controller to increase engine speed so that the propulsion unit produces thrust at least equal to the minimal propulsive force needed to effectively steer the watercraft.
U.S. Pat. No. 6,524,146, which issued to Spade et al. on Feb. 25, 2003, describes a watercraft having auxiliary steering. A control mechanism for a watercraft includes a selectively movable flap connected to an actuator, which moves the flap into and out of the flow of water to affect steering, deceleration and trimming. The flap is recessed with respect to the lower surface of the hull so that it does not create drag at high speeds. The flap may be a portion of the ride plate, may be disposed in a recess in the bottom of the hull, or may be disposed on the stern above the bottom of the hull.
U.S. Pat. No. 6,561,860, which issued to Colyvas on May 13, 2003, describes a maneuvering enhancer for twin outboard motor boats. An adjustable length bar is used to replace a rigid bar, the one connecting the two outboards or the two outdrives of a boat, for steering purposes, said adjustable bar being electrically operated through a switch on the boat's dashboard, said switch having two operating positions, one to keep propellers creating two parallel thrusts, and a second to shift the propellers to create a vee configuration, by which the boat's maneuverability will be enhanced.
U.S. Pat. No. 6,997,763, which issued to Kaji on Feb. 14, 2006, describes a running control device. A running control device for a watercraft controls propulsion force and tilt angle of a propulsion device relative to the hull of the watercraft. The running control device also sets an optimum trim angle automatically. The running control device includes a propulsion force control section that controls the propulsion force of the propulsion device. The running control device also includes a tilt angle control section that controls the tilt angle of the propulsion device. A target propulsion force calculation module responds to first input information to calculate a target propulsion force. An amount-of-operation calculation module responds to second input information to calculate an amount of operation of the propulsion device to produce the target propulsion force. The tilt angle control section includes a tilt angle calculation module that determines the tilt angle based on the propulsion force.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.